Two more impossible newcomers ideas came to my mind.
Parin from Gurumin
Her moveset is basically already done, she has a lot of moves already and most of them are perfectly compatible with the Smash moveset structure, including neutral moves, taunts, idle animations, roll/dodges and victory animations: probably only shield and grab animations are missing.
She's basically Jill from Drill Dozer minus the mech, and she would have an unique gimmick of leveling up her drill by inflicting damage without being hit (and downgrading it when hit).
The drill has 3 levels: drill levels would make her attacks slighty stronger (kinda like Lucario's aura) and change the effect of the special moves that will get additional range and slighty different animations (other than changing the drill's appearance).
Her down special would have ice elemental properties, her neutral special would have fire elemental properties, and her up special would have lightning elemental properties; up special would be similar to Link's; side special would be similar to a mix between Sonic's Homing Attack and Falcon's up b (or those Diddy and Sheik's special moves where they launch themselves onto the opponent), without elemental properties.
For final smash, she has 4 options:
-break the jar containing the energy of a monster, and summon it; said monster would probably be Black Bean (an overpowered boss).
-capture the opponent and do a cutscene-type final smash where all the monsters are summoned and attack all together in a funny way
-Lv 4 drill, captures an opponent with the auto aiming components of the drill, then charges a strong hit and attacks
-the drill transforms and becomes huge, allowing Parin to do a very powerful attack (this does not happen in the source game but I think it would be fitting, also as a Gurren Langann reference).
Last but not least, she also has many outfits that can be used for alt costumes.
(This post makes me sad because it reminds me of how cool Jill would be in Smash, and that it will never happen; she was scrapped as assist trophy and apparently nobody cared, and if that was not enough, Bowser Jr stole her role by fighting in a "mech" and using drills to attack. Too bad, she could have had some unique 3-gear smash attacks and the gimmick of inverting the rotation of the drill to capture the enemies or launch them away).
Cookie & Cream from The Adventures of Cookie & Cream
They are a duo like the Ice Climbers.
In their game, they cooperate in order to solve puzzles and go thorugh some platforming levels. The screen is usually split in 2, and the two rabbits are stuck into their one side of the screen, often in need of the help of the other one in order to procede.
Aside of using the hammer for smash attacks, their moveset would be based on summoning and using gimmicks, they don't even need to be taken directly from the original game... as long as it's a crazy gimmick where both rabbits have to cooperate, then it's fine (developers can go very creative with these two).
They can also use a banjo and maracas to play music and attack... Cream especially can attack creating shockwaves with the Maracas in the DS version of the game.
As for the final smash.... well...... they would not be much different than Skull Kid, they would summon the moon that would crush the stage and deal massive damage to anyone in the way.
The funny thing: the game is developed by From Software, the same company behind Dark Souls; Cookie & Cream are definitely the most likely From Software reps, isn't it?
(Also, lol, another "Cream the Rabbit" exists in the world of gaming and has absolutely no connections with the other one, aside of the name, the animal species, the gender, and being part of a duo).
I'm not sure but this may be the first time someone on this planet mentioned Cookie & Cream and Smash Bros together.